Specific utilization rate

A more useful model is the ATP maintenance energy model. The specific utilization rate of ATP can be expressed as ... 

Maximum utilization rate of specific soluble organics (km)... 

FIGURE 27.13 Specific soluble organics utilization rate versus the limiting soluble organic concentration. 

U Specific soluble organics (i.e., substrate) utilization rate, the change of soluble organics... 

Microbial Biotransformation. Microbial population growth and substrate utilization can be described via Monod s (35) analogy with Michaelis-Menten enzyme kinetics (36). The growth of a microbial population in an unlimiting environment is described by dN/dt = u N, where u is called the "specific growth rate and N is microbial biomass or population size. The Monod equation modifies this by recognizing that consumption of resources in a finite environment must at some point curtail the rate of increase (dN/dt) of the population ... 

In the following, the basic principle of the flexible recipes is presented. To keep the explanations simple, we consider only one single type of end product that is produced from one single raw material on one resource at a specific location during a given period. Required are the maximum process throughput of the resource measured in tons of output per hour and the input of raw material and output of finished products, respectively. In many types of chemical mass production, raw material consumption depends on the utilization rate of the equipment employed. Hence, linear recipe functions can be derived, which indicate the input of raw material required to produce the desired amount of output. 

The oscillatory behavior of fermentors can be investigated utilizing such a model. Here the synthesis of a cellular component that is essential for both growth and product formation depends nonlinearly on the ethanol concentration. Hence the inhibition by ethanol does not directly influence the specific growth rate of the culture, but it affects it indirectly instead. 

Figure 4 shows the growth profiles of D. hansenii in nondetoxified (pH 5.5) and detoxified hydrolysates, both nonsupplemented and supplemented with several nutrients. Similar specific growth rate and biomass yield were observed for all nonsupplemented hydrolysates regardless of the utilization of a detoxification step (Table 3). A similar pattern occurred... 

Some models utilize the concept of Luedeking and Piret (1959) for growth associated and/or non-growth associated production (Equations 65 to 67). However, in some circumstances, the best fit occurs when the specific death rate kj is considered, instead of the specific growth rate px (Equations 68, 70 and 71) (Linardos et al., 1991 Zeng, 1996a, 1996b). This statement follows the observation that antibody production increases when cells are under conditions of stress. 

First, solve for rsu using the information given in the table and the following equation, in which X is biomass concentration, S is growth-limiting substrate concentration, and Ks is the substrate concentration at one-half the maximum specific substrate-utilization rate ... 

Specific substrate utilization rate—Amount of substrate consumed per unit amount of organisms produced. 

The effect of potassium on the kinetic constants is illustrated in Figure 15. Only the maximum specific growth rate, km, and the maximum specific substrate utilization rate, k, were affected by increases in potassium. These data were used to plot Figure 16, which indicates that the toxic effect of high concentrations of potassium is caused by a reduction in the rate at which each methane organism can process acetate. 

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